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Why Astronomy Needs Low-Pressure Sodium Lighting
Abstract
The damage to the dark-sky resource upon which ground-based astronomical observatories depend is substantial and increasing, even at what are considered premier dark-sky sites. Due to its nearly monochromatic output at the Na I resonance doublet near 589 nm, extensive use of low-pressure sodium (LPS) lighting in areas near astronomical observatories offers the potential preservation and even restoration of dark skies at other wavelengths, as well as minimal impact on the lighting needs of surrounding communities. Flagstaff, Arizona, with extensive use of LPS for general area lighting, has shown that this goal can be achieved.
... The artificial sky brightness effect on the astronomical observation can be mitigated by using Low-Pressure Sodium-vapor lamps (LPS) (or Light Emitting Diodes -LEDswith a similar spectral emission) in the exterior lightings located around the observatory, including in streetlights (CIE 150, 2017). LPS lamps are preferred in surroundings near to observatories because they emit light in very narrow spectral lines, mainly in a narrow band of 589nm (Figure 16), because generate a small interference with astronomical observation (Luginbuhl, 2001). At far away distances from the observatory lighting technology requirements are less restrictive. ...
... A protection radius of 100km has been proposed based on the minimal protection distance indicated by international recommendations (CIE 126, 1997;ILP GN01, 2011;CIE 150, 2017). On the other hand, a reduction of emissions in the blue spectrum band is proposed based on international recommendations (CIE 150, 2017), as documented in the scientific bibliography (for example : Luginbuhl, 2001;Luginbuhl et al., 2009;Luginbuhl et al., 2014), and demonstrated using light pollution propagation models in the North Zone of Chile. ...
Through the CVE1578632 resolution of April 24th, 2019, the Chilean Ministry of
Environment started the review of the Norm of Emissions for the Regulation of Light Pollution DS043/2012 MMA. On May 31st, 2019, the Office for the Protection of the
Qualities of the Skies of Northern Chile OPCC delivered to the MMA the document
named Proposals from the OPCC for the Review of the Standard of Emissions for the
Regulation of Light Pollution and its Related Systems Due to the high impact caused by
the light pollution in the operation of the major astronomical observatories, and the urgent need to reduce the current levels of deterioration of the night sky, it has been proposed a set of measures that reduce the limits of spectral emission in zones close to the observatories. This document is a comprehensive justification of these proposals
regarding to the limitation of the radiance magnitude and the light emission in bands lower than 500nm, to set a protection radius and to establish a national zone classification.
All astronomical observations are essentially an observation of contrast. Any stray light causes a veil, reducing all contrasts. Sky glow is disability glare. This hold for all sources. Diffraction makes even point sources into surface sources. The decrease in the limiting magnitude as a result of the veiling luminance is expressed in the ‘sky glow formula’. Over the years, many measurements of light pollution have been made regarding the distribution in place and time, both local and regional. Satellite observations made it possible that in 2001 ‘The First World Atlas of the Artificial Night Sky Brightness’ was published. It is found that about two-thirds of the world population is subject to light pollution. For 25% of the world population, only the brighter stars can be seen, but not the Milky Way. For 85% of the population in the Netherlands, the artificial light exceeds that of the full moon, and in only 3% of the area of the country, the artificial brightness is less than the natural brightness. The Atlas is based on measurements that are made by the Defense Meteorological Satellite Program (DMSP). In spite of considerable efforts to avoid it, sky glow did increase considerably on a global scale over the last few years. At present, it seems safe to expect that the levels of light pollution at most locations in the world are increasing and that they will go on increasing for the foreseeable future. A rate of increase is difficult to guess but it might seem that 3% per year will not be too far off. It should be noted that 3% per year means a doubling in 23 years.
This paper has been withdrawn and replaced by quant-ph/0609207.
The U.S. Defense Meteorological Satellites provide an opportunity to measure the uplight produced by artificial lighting on the ground. In this study DMSP data are used to measure the integrated at-detector radiance of a number of communities in the American Southwest in an attempt to evaluate the effectiveness of outdoor lighting codes. Use of DMSP data in this manner is complicated by many factors, and some of these are briefly discussed.
Under monochromatic illumination, such as that produced by low-pressure sodium sources, only variations in lightness can be perceived. This paper investigates the degree to which the addition of small amounts of full-spectrum incandescent illumination can improve colour categorisation.
Results are reported of a program to determine the brightness of the
night sky at Kitt Peak during the recent solar minimum. Well-calibratd
photometry in B and V suggests that the average brightness of the night
sky during this period was approximately V = 21.9, B = 23.0 in
magnitudes per square arcsec, but that variations of a few tenths of a
magnitude can occur from night to night, or even during a single night.
Since 1987, the sky has already brightened considerably, probably due to
the increase in solar activity as the sun moves toward sunspot maximum
in 1991.